The present invention relates to composite articles of frozen confectionery comprising distinct inclusions of fillings in the mass of a frozen composition.
It is known how to incorporate and uniformly distribute pieces, for example pieces of comfits or dried fruits, in a mass of frozen composition, for filling pots or trays in the manufacture of family or bulk portions. The device described in DE-A-3521612, for example, makes it possible to distribute uniformly already formed pieces of a certain size in a vein of ice cream, from a hopper with the aid of a rotating drum with retractable blades pressing against a cylindrical wall, the function of which is to load a constant quantity of pieces into a sector of the drum and to distribute it uniformly in the stream of ice cream.
In U.S. Pat. No. 3,014,437, for example, different masses of plastic products such as ice cream masses with different flavors are co-extruded in the form of extrusions, and they are then twisted by imparting a rotating movement with the aid of a rotating blade in the form of a butterfly. One of the plastic products may be a fondant.
The object of the present invention is to meter into a frozen composition inclusions which in particular have a different composition, color and flavor from those of the frozen composition and to distribute them in a random manner in the mass, so that there is a distinct, preferably contrasted, separation between the inclusions and the frozen composition and so that the inclusions are not clustered together by gravity, for example at the bottom of a container during filling.
The article according to the invention is characterized in that it comprises a mass of frozen composition and a filling in the form of inclusions which are stabilized and distributed in a random manner in the mass of frozen composition and in that the inclusions are produced by the co-extrusion of a liquid central filling that can be pumped and a frozen composition that can be extruded at a temperature of less than or equal to about xe2x88x928xc2x0 C.
According to the invention, a xe2x80x9cfrozen compositionxe2x80x9d is understood to be an ice cream, a sorbet or a sherbet, which is aerated or expanded to a variable extent, or a frozen culinary mousse which is aerated to a variable extent.
Within the context of the invention, a filling consists of an aqueous or fatty composition having a dry matter content of preferably about 28 to 80 wt. %, and containing a sugar.
As a sugar, use may be made of granulated sucrose, polysaccharides, more particularly a glucose syrup, burnt sugar, invert sugar, or a maltodextrin, more particularly those having a high dextrose equivalent, for example approximately 100.
The filling may consist of a fruit or vegetable puree, preferably pure, i.e. without any additive. The filling may optionally contain a minimum quantity, much lower than that normally used, of a gelling or thickening agent such as, for example, a gum, a pectin or a gelatin.
The filling may be honey, caramel or fruit puree and may have been prepared from a paste of dried fruit, praline, nougat or nougatine. It may contain flavorings and colorings, for example chocolate, coffee, or fruit flavorings and, optionally, preservatives.
Such fillings may contain small inclusions such as, for example, fragments of chocolate or dried fruit.
The filling may be in the form of a fondant or of a paste with a fatty composition, optionally aerated, for example a fruit or chocolate mousse.
According to the nature of its composition, the filling will result in solid inclusions in the mass of the frozen composition that are hard or liquid to a varying extent and that are viscous to a varying extent. It is important that the filling can be pumped and can be conveyed to the outlet die.
The invention also concerns a process for manufacturing a frozen composition containing inclusions, characterized in that extrusions of a central filling surrounded by a sleeve of frozen composition are formed by co-extrusion at a temperature for the frozen composition of less than or equal to xe2x88x928xc2x0 C., and in that the extrusions are processed into a mass of frozen composition incorporating the inclusions distributed in a random manner in the mass of frozen composition.
In the process of the invention, it is important that the frozen composition can be extruded at a very low temperature and dissipates the energy that it has stored up in the form of negative calories on leaving the extrusion die, so that the emerging co-extrusion can be shaped. This can be achieved, for example, by coiling up the extrusion or folding it on itself by means of a moving co-extrusion nozzle, continuously delivering a coiled or folded extrusion at the outlet from the die, which can then be cut into portions, or it can be achieved by filling a container by means of a static co-extrusion nozzle, in a discontinuous manner. Such a container may be a pot, a cornet, a tray for a family or xe2x80x9cbulkxe2x80x9d portion or an ice lolly mould. In this method of filling a container, the co-extrusion nozzle may be given an up-and-down movement, for example so that it falls to a level close to the bottom of the container and then rises as the extrusion is metered in. During this operation, the container may remain stationary or, as a variant, the nozzle may remain stationary and the container moves during filling. When the nozzle moves, provision is made for it to be connected to the extruder by a flexible connection.
In practice, the extrusion has a certain plasticity over a certain period of time, for example of the order of about 10 seconds. It should be noted that, according to the invention, the Theological properties of the filling do not play a determining part in achieving co-extrusion. Thus it is possible to manufacture a composite extrusion and to shape it, in particular in a container, without taking special precautions as regards the physical properties of the filling, in particular its viscosity and density, relative to those of the frozen composition, since the stability of the inclusions is ensured by the state of the frozen composition surrounding the filling. The process of the invention also permits a large variation in the choice and nature of the fillings.
In principle, any process enabling a frozen composition to be extruded at a very low temperature is applicable. It is preferable to use a single-screw or twin-screw extrusion apparatus, in which cooling and incorporation of air is carried out in a single apparatus.
According to a preferred embodiment of the process, the raw materials making up the composition to be frozen are passed through a device provided with two parallel endless screws, revolving in the same direction.
According to a particular embodiment, a gas, for example air, is injected into the barrel in sufficient quantity to provide an overrun of about 20 to 150% and preferably 80 to 100%.
In order to put the process into practice, a composition is prepared in a conventional manner for ice cream, low-fat ice cream, sorbet or sherbet, based, according to the recipe, on milk, skimmed milk, cream, concentrated milk, milk powder or butter oil to which has been added sucrose, glucose, fruit dextrose, fruit pulp or vegetable pulp and stabilizing hydrocolloids, such as, for example, carrageenates, alginates, carob gum, and emulsifiers, as for example partial glycerides, and flavorings. After mixing the ingredients intimately in the proportions dictated by the recipe, the mixture is pasteurized and cooled and then, optionally, it can be homogenized, preferably hot, under stringent conditions. After cooling the homogenizate to a low temperature, approaching 0xc2x0 C., the composition may be left to mature for a certain time at this temperature. Homogenization and maturing are optional stages.
This mass, which is optionally homogenized and matured, is referred to in the following description as the xe2x80x9cmass to be frozenxe2x80x9d. It is introduced, preferably at approximately 2-5xc2x0 C., into a twin-screw freezing device which will be described below in greater detail, in which it is blended by the co-rotating screws revolving at high speed, preferably at about 100-600 revolutions per minute, is led to an air-injection zone where it is expanded by about 20-150%, is strongly cooled to about xe2x88x928xc2x0 C. to xe2x88x9220xc2x0 C., and is then forced through a die.
The work is carried out in the twin-screw device, surprisingly, without excessive shear, so that the pressure increase does not exceed approximately 50 bar at the die. The emerging product is characterized in that it has a mean ice crystal diameter of between about 20 to 60 microns and a mean equivalent diameter for the ice crystals of about 32 to 36 microns. These values are appreciably lower than can be obtained with conventional freezers. The term xe2x80x9cice crystal diameter,xe2x80x9d as used herein means the largest cross sectional distance of the ice crystal. The term xe2x80x9cequivalent diameter,xe2x80x9d as used herein means the diameter of a circle that has an equivalent surface area as the surface of the crystal. The term xe2x80x9cmean,xe2x80x9d as used herein is the arithmetic mean of measurements taken on several ice crystals. The ice crystal size may be readily determined by one or ordinary skill in the art using a dispersion of ice crystals in mineral oil at xe2x88x9210xc2x0 C. Ice crystal size may be determined, for example, by the method disclosed in xe2x80x9cDetermination of Ice Crystal Size Distributions in Frozen Desserts,xe2x80x9d by D. P. Donhowe et al., J. Dairy Sci., 74: 3334-3344 (1991), the contents of which are expressly incorporated herein by reference. The frozen aerated product of the invention also has smaller air cells and there is less coalescence of the air cells compared to prior art products. The frozen aerated product of the invention also has fat globules, as determined by the Malvern method (laser scattering) in the melted liquid state, that are less than 20 microns, preferably from about 4-20 microns, and more preferably from about 8 to 20 microns. The result is an improvement in texture as regards better oiliness and better creaminess.
The filling is injected into the heart of the vein of frozen composition leaving the extruder, by means of a co-extrusion nozzle at the outlet from the barrel of the screw extruder, a nozzle which, as indicated previously, may be moving or static.